It’s likely that you will have some videos or movies that’s to be uploaded to YouTube, unfortunately, you may find the file is far too large to upload. Any there any ways to reduce the video size without sacrificing the quality? Just follow the 5 ways below to compress your large video with no quality loss.
Basics about video compression
How compression works?
Before perform the video compression task, you should understand how compression works. Video is typically filmed with 24 or 30 frames per second. That means that every second, 24 or 30 still images are displayed to give the illusion of movement. Because the images are so closely linked, not everything in the image moves from frame to frame. Compression stores the changes in the frames as opposed to storing entire frames.
Terms that related about video compress
There are several key terms that you will come across constantly as you start compressing more videos. Learning these terms will help you make sense of the options you have while compressing a video.
Codec ： This is a method that your computer uses to decide on the amount of change that occurs between frames.
Keyframe ： This is a reference frame. The codec will determine a keyframe every few frames. This is the base frame for the next few frames of change. Your keyframe interval will have a large impact on the size of your finished file. Lots of keyframes will make the file large but higher quality. Infrequent keyframes will leave lots of artifacts.
Artifacts – These are blocky pieces of image that are the result of the keyframe not being updated correctly. The lower the quality of the compression, the more artifacts that will appear.
Bit/data rate – This is the amount of data that each second of video uses. Typically, this is measured in kilobits per second. Bit rates can be either Constant or Variable. A constant bit rate stays the same throughout the video, which can lead to larger video files. A variable bit rate changes depending on the amount of action on the screen, which will lead to smaller files.
Variable bit rates: Which can decrease quality if the bit rate does not change dynamically enough with the video. Experiment with both bit rates to find a balance between size and acceptable quality.
Frame rate： this is the number of frames per second. Videos are typically shot in 24 or 30 frames per second. Keep the compressed copy’s frame rate the same otherwise playback will be affected and audio may not sync properly.
Resolution ： This is the size of the outputted video. It is measured in pixels, width x height.
Compress video for YouTube/Vimeo
1. Understand why you need to compress. Raw video files, especially HD video, can run several gigabytes in size. While you can upload large files to YouTube and Vimeo, this can take a very long time. Also, these services will compress your file once it is uploaded, and often the results are not very high quality. Compressing your video yourself allows you to control both the size and the quality.
2. Open your raw video file in a video editing program. There are free solutions available online, as well as professional products such as After Effects, Final Cut, and more. The specific menus will vary between programs, but the settings are universal across all platforms.
3. Export the video. In order to start the compression process, you will need to export the video. This will convert the video into a format that is playable on all systems and devices, including formats supported by YouTube and Vimeo.
4. Select the file format. The file format will change depending on what you plan on doing with the final file. Most systems and devices will play MP4 files, making it the most universally accepted file type. This includes game systems like the PlayStation 3.
5. Select the video format (codec). H.264 is the most widely used codec and is supported by the most systems. This is the preferred codec for uploading videos to be streamed online. HD video should be encoded in High Profile H.246.
6. Select the bit rate. For SD video, use a bit rate between 2,000-5,000 kbps. 720p video should have a bit rate between 5,000-10,000 kbps. 1080p video should have a bit rate of 10,000-20,000 kbps.
7. Select resolution (image size). Try to keep it the same as your raw video. Streaming websites will add in their own resolution options after the uploading process.
8. Adjust the keyframe and frame rate. Encode your video in the same frame rate that you recorded it in. If you recorded above 30 frames per second, encode in half that (for example, a 60 FPS video would be encoded at 30 FPS). Keep the keyframe the same as the frame rate.
9. Select encoding mode. In general, go for multi-pas (Best) encoding. This will take longer than a single-pass, but will result in a noticeably higher-quality video.
10. Set your audio options. Choose AAC-LC as the audio format, as this has the widest support and the best quality. For data rate, select 320 kbps. If you have music, choose Stereo. If you do not have music, select Mono. Your output sample rate should be 48.000 kHz
Use QuickTime X
1. Open the movie in QuickTIme. This method is primarily for .mov files. These are proprietary Apple QuickTime files. These files are already compressed, but can be compressed more for uploading to the web or transferring to your phone.
2. Click the File menu. Select Export To and then Web. This will open a window with several options. You can change the name of the movie file if you’d like to distinguish between the original and the compressed copy.
3. Select your quality. You will be given three quality options when you export your movie. You can pick between Wi-Fi, Cellular, or Web. Choose the format that best suits the the method that you will be playing back the video.
Cellular will provide the smallest size and the lowest quality. Use this if you will be watching the movie on a phone or tablet.
Wi-Fi will provide medium quality and medium compression size. Use this if you will be streaming the video file over your home wireless network.
Broadband will provide the highest quality compression, but will result in a file that is not much smaller than the original. Use this option when uploading a video to be streamed online.
You can check multiple boxes to create multiple copies of the movie file with different compressions.
Using Finder (OS X 10.7 )
1. Open the Finder. Navigate to the movie file on your computer. This method only works with QuickTime movie files (.mov).
2. Right-click the file. Click Encode Selected Movie File from the bottom of the menu. This will open the Encode Media pop-up window.
3. Choose your settings. In the Setting menu, choose the resolution that you would like to encode the movie in. 1080P is the highest setting, and is the standard Hi-Definition resolution. 720P is lower quality but is also considered Hi-Definition.
Choosing a resolution higher than the original resolution will not result in a better looking movie.
You can also choose to just extract the audio in the Setting menu.
4. Select compatibility. If you plan to watch the movie on multiple devices, select “Greater compatibility” from the “Encode for” menu. This will make the format H.264 video and AAC audio, one of the most compatible formats available.
5. Encode the movie. Once you are satisfied with your settings, you can start the encoding process. You can see the target data rate and resolution in the Encode Media window, as well as compatible devices. Choose your destination and click Continue when you are ready.
Using QuickTime 7 Pro
1. Open the movie file in QuickTIme 7 Pro. This method is for compressing .mov files. Open the Inspector by pressing Command + I. This will open a window showing you the basic properties of the movie file.
2. Resize the movie. If you want to make the movie smaller, click and drag the corner of the movie to resize it. If you are aiming for a certain size, watch the Current Size readout in the Inspector window to see what dimensions the video is currently showing in.
1080p is 1920×1080 pixels.
720p is 1280×720 pixels.
3. Open the File menu. Select Export. In the Export menu, select Movie to QuickTime movie. Click the Options button and then the Video Settings button to set your compression preferences.
For greatest compatibility, set the compression type to H.264. This will ensure that the file is playable on most systems and devices.
Set Frame Rate to Current. This will keep the frame rate the same as the original file, which will ensure smooth playback.
Key Frames and Data Rate should be set to Automatic. These settings are for advanced users.
4. Adjust your Compressor quality. Adjust the slider in the Compressor section to adjust the final quality. Lower quality will mean a smaller file, but will have more artifacts in the final compression. Best quality will result in very little change in the file size, but will give the highest picture quality.
Select “Best quality (Multi-pass)” to produce the highest quality compression. This will result in a much longer encoding process. If time is an issue, run “Faster encode (Single-pass)”, though this will result in a poorer quality final product.
5. Adjust the sound settings. Click the Options button and then click Sound Settings. In this window, select AAC as the format to make sure that most devices can play the audio. If the video has music, set Channels to Stereo. If the video does not have music, or does not utilize surround sound, select Mono. Mono will lead to a smaller file size.
Set Rate to “48.000”. This will keep the file size down without sacrificing audio quality too much.
6. Click Show Advanced Settings. Set Quality to Normal in the Render Settings section. Encode Strategy should be sent to Average Bit Rate, and Target Bit Rate should be set to 40 kbps.
You can adjust these settings as you see fit to change your final compressed video.
These settings are optimized for uploading videos to video streaming websites such as YouTube and Vimeo.
7. Prepare it for uploading. Check the Prepare for Internet Streaming box in the Options menu. Select Fast Start and press OK.
Original source:
http://www.wikihow.com/Compress-Video
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